1. Field of the Invention
The present invention relates in general to window regulators for automotive vehicle doors and more particularly to a device for guiding upward and downward movement of a door glass or window pane of an automotive vehicle door.
2. Description of the Prior Art
An example of a prior art device for guiding upward and downward movement of an automotive vehicle door is shown in FIGS. 4 and 5. In the drawings, a pair of forward and rearward guide rails are generally indicated by the reference numerals 1, 2 and disposed within a door main body 3a of an automotive vehicle door 3 to be installed thereon. The guide rails 1, 2 have a U-shaped cross section and each include a pair of parallel side walls 1b, 1c or 2b, 2c and a connecting wall 1a or 2a interconnecting the side walls. The guide rails 1, 2 are arranged so as to be turned at the connecting walls 1a, 2a toward each other. The side walls 1b, 2b located closer to a door glass 4 are respectively formed with V-shaped grooves 1d, 2d. Carrier plates 5, 6 are secured to a lower end portion of the door glass 4 with bolts and nuts 7 and each of which in turn carries thereon by way of shafts 10, 11 a pair of upper and lower guide rollers 8 or 9. The guide rollers 8, 9 are movably engaged with the corresponding guide rails 1, 2 so that the door glass 4 is movable upwardly and downwardly being guided by the guide rails 1, 2. The similar structure as above is disclosed in the Japanese Utility Model Publication No. 58-50275.
A disadvantage of the prior art device is that the door glass 4 can swing forwardly and rearwardly of the vehicle when subjected to a certain force applied thereto from a drive unit of an associated window regulator since the distance between the side walls 1b, 1c or 2b, 2c is designed larger than the diameter of the rollers 8 or 9 so that the rollers 8, 9 are movable smoothly being guided by the side walls. In a particular case, one pair of rollers 8 or 9 can be moved out of the groove 1d or 2d as shown by the two-dot-chain lines in FIG. 5. For the above reason, the prior art device is not highly reliable in operation and liable to be lowered in quality.